Mishna: A person who intends to misappropriate a deposited item [Rashi: and announces that intention before witnesses]: Beit Shammai says he is liable [Rashi: from the moment he declares his intention]. Beit Hillel says: He is not liable until he actually misappropriates [literally, "he puts his hand on it"], as it says [Ex 22:7,10] "If he did not put his hand on his fellow's property."
If he [a custodian] tilted a keg and took a r'vi'it [a fluid measure, approximately a pint or half a liter], and it broke [i.e., the keg broke accidentally at some later time], he is liable only for the r'vi'it. If he lifted the keg and took out a r'vi'it and it later broke, he pays the entire cost [of the keg]. [Rashi: To be liable for the keg, the custodian must perform an act to acquire the keg. Tilting the keg is not an an act of acquisition, but lifting it does and thus establishes liability for the misappropriation.]
Gemara: From where are these rules) derived? As the rabbis taught [in a b'raita]: "For every act of negligence" [Ex 22:8, referring to an unpaid custodian]. Beit Shammai says: This teaches that he is liable for intent just as he is liable for the act. Beit Hillel says: He is not liable until he actually misappropriates [literally, he puts his hand on it"], as it says [Ex 22:7-10] "If he did not put his hand on his fellow's property."
Beit Shammai said to Beit Hillel: But it already says "For every act of negligence" [implying liability even for intention].
Beit Hillel said to Beit Shammai" But it already says "If he did not put his hand on his fellow's property" [implying the requirement of actual physical misappropriation]. So why does the Torah state "for every act of negligence?" We might have assumed that this (the liability) applies only when he (the custodian) performed the act himself; how do I know (that he is liable) for the misappropriation of his servant or agent? The Torah says "for every act of negligence."
[Our mishna:] If he tilted a keg ..." Rabbah said: This [that he is not liable] is only if the keg was broken. But if the wine turned to vinegar, he pays for all of it. Why? Because it was his arrow that caused the spoilage [i.e., the custodian's removal of the r'vi'it, thus exposing the remaining wine in the keg to the air, caused the subsequent spoilage].
[Our mishna:] If he (the custodian) lifted the keg and took (a r'vi'it) from it. Shmuel said: "He took" does not (necessarily) mean he literally took. But because he lifted it to take, (he is liable) even if he didn't take from it.
Does this imply that Shmuel holds that misappropriation does not require loss?
Perhaps not, for this is a special case, (for the custodian) the entire keg serves as a container for the r'vi'it (that he intends to misappropriate). [Rashi: Perhaps Shmuel holds that misappropriation ordinarily does require loss. But in the present case, the custodian is, in fact, borrowing the entire keg of wine -- the r'vi'it that he wants for himself, plus the remainder, which serves to protect that r'vi'it from spoilage, and we have learned that borrowing without the owner's permissions equivalent to robbery (See bm43b.1).]
Rav Ashi asked: If he [a custodian] picked up a purse to misappropriate a coin, what is the law? [Does he become liable as soon as he picks up the purse, or not until he takes the coin?]
Perhaps [he is liable] only in the case of wine, which is safe (from spoilage) only when kept with other wine [in a full container], but coins are safe by themselves [so he would not be liable]? Or maybe the security of a purse is greater than the security of a single coin [i.e., the purse is less likely to be misplaced, so that the case of the wine and the case of the coins are parallel]?
Let it stand [i.e., the matter remains unresolved].